Daikin vs Mitsubishi heat pumps: SCOP, noise and warranty compared

Quick answer: For a radiator retrofit, Mitsubishi’s Ecodan R290 is the stronger buy. The 8.5kW unit is MCS-listed at SCOP 3.51 at 55°C and reaches 75°C flow. Daikin’s Altherma 3 M manages 3.28 to 3.35 at 55°C and runs louder at 58 to 62 dB(A) sound power.

We haven’t tested either of these units. Everything below comes from manufacturer datasheets, warranty documents and UK trade listings, all checked on 28 July 2026 (Mitsubishi’s datasheet figures re-checked on 25 September 2026). Where a figure isn’t published, we say so rather than guess.

What you’re actually comparing

Both brands sell several ranges, and installers rarely explain which one they’ve quoted. Mitsubishi’s current residential monobloc is the Ecodan R290 (PUZ-WZ50VAA up to PUZ-WZ120VAA), which replaced the older R32 Ecodan for most retrofit work. Daikin’s volume seller is the Altherma 3 M, an R32 monobloc, with the newer R290 Altherma 4 arriving in stages: the EPSK series from April 2025 and 4, 6 and 7kW EPSKS classes announced on 15 January 2026 (Daikin press release).

That timing matters. If your quote says Altherma 3, you’re being quoted an R32 low-temperature machine; if it says Altherma 4, you’re getting propane and a higher flow ceiling. They are not interchangeable.

The numbers side by side

Efficiency: the 35°C number is a distraction

At 35°C flow the two are close. Daikin’s 8kW Altherma 3 M posts 4.61, Mitsubishi’s 8.5kW posts 4.47. On a house with underfloor heating throughout, you would not notice the difference on your bill.

At 55°C the gap opens. Mitsubishi’s 3.51 against Daikin’s 3.35 is about a 5% efficiency advantage, and almost every British retrofit runs above 35°C. Take a home needing 12,000 kWh of heat a year. At electricity’s 26.32p/kWh under the October to December 2026 price cap, SCOP 3.51 costs roughly £900 a year against £943 at 3.35. Around £43. Real, but not the thing that should decide your purchase.

One caveat that people get wrong constantly. Mitsubishi quotes SCOP (MCS) while Daikin quotes SCOP to EN 14825, and those are close cousins rather than the same test, so reading one against the other is directional at best. Our guide to what COP and SCOP mean for your bills goes through why.

Noise, and why Mitsubishi wins it

Mitsubishi publishes 56 dB(A) sound power for the 5kW and 54 dB(A) for the 8.5kW, with 40 dB(A) sound pressure at 1 metre. Daikin’s Altherma 3 M runs 58, 60 and 62 dB(A) across 4, 6 and 8kW. Between the smallest units that’s two decibels, which sounds trivial. At 8kW it’s eight. In the MCS 020 sound calculation, which every England installation has needed since 29 May 2025, four decibels can be the difference between permitted development and a planning application.

Daikin’s answer is the Altherma 4, and its marketing for that range leans on a very low decibel headline. Whatever figure you are shown, check whether it is sound pressure at a stated distance or sound power to EN 12102, because only the second one describes the machine. Daikin’s own announcement of the 4, 6 and 7kW classes carries no sound data at all, and we couldn’t find a full EN 12102 sound power table for the UK Altherma 4 range. Until one exists, treat any headline decibel claim for it as marketing. Our piece on heat pump noise and planning rules explains which number your installer actually has to use.

Warranty: Mitsubishi’s floor is higher

Daikin gives 2 years as standard. You get to 5 years free if a Daikin Sustainable Home Installer fits it and you register on Stand By Me within two years of commissioning, and up to 7 years only as a paid extension through a Sustainable Home Expert. Annual maintenance is a condition throughout.

Mitsubishi runs a three-tier structure instead: up to 3 years as standard, up to 5 through an Accredited Ecodan Installer, and up to 7 through a Business Solutions Partner. Mitsubishi doesn’t publish a price against those tiers, and the registration deadline sits in the terms and conditions rather than on the warranty page, so get both written onto your quote.

So the ceilings match at 7 years. What differs is the route. Daikin’s final two years are an explicit paid extension, bought through a Sustainable Home Expert; Mitsubishi’s top tier is tied to installer accreditation instead. If your installer can’t tell you their accreditation tier, that’s your answer about which warranty you’ll actually get.

Price

Supply-only, the Ecodan R290 PUZ-WZ80VAA, which The Heat Pump Warehouse sells as its 8.5kW, listed there at £3,449.38 excluding VAT on 28 July 2026, and at the same price on 25 September 2026. We couldn’t find a like-for-like single-unit UK listing for the equivalent Daikin EBLA08EV3 the same day, so we won’t put a number against it. That’s worth knowing in itself: more of Daikin’s volume moves through installer channels than off the shelf. Either way a supply-only price sits well above what a fitter pays, so read it as a band rather than a quote. Fitted, our heat pump cost index puts a typical three-bedroom air source job at £10,684 including VAT, before the £7,500 Boiler Upgrade Scheme grant. The method is on how we calculate costs.

The verdict

Buy the Ecodan R290 if you’re keeping existing radiators, if the unit is going anywhere near a boundary, or if your installer is a Mitsubishi Business Solutions Partner. It’s quieter, and it’s better at the flow temperatures British retrofits actually run at.

Buy Daikin if you’re on underfloor heating throughout, where the 55°C gap stops mattering, or if the only competent installer near you is a Daikin specialist. Fitter quality moves your bills more than a 0.2 difference in SCOP ever will. And if you’re being quoted an Altherma 3 for a Victorian terrace with 70°C radiators, push back: that’s the wrong machine for the job. Compare the wider field in our best heat pump brands guide, or size the job first with the cost calculator.

FAQs

Is Daikin or Mitsubishi more reliable?

Neither publishes failure-rate data, and nobody independent collects it in the UK. Consumer review scores exist for both parent companies, but they pool air conditioning, spares and call-outs in with heat pumps, so they tell you very little about these specific units. Judge on warranty terms and installer accreditation instead.

Can the Altherma 3 replace a gas boiler on existing radiators?

Sometimes, but its 65°C ceiling and 3.3 SCOP at 55°C mean you’ll want a proper heat loss survey and probably some larger radiators. The Ecodan R290 and Altherma 4 both reach higher flow temperatures if you’d rather not change emitters.

Do both qualify for the £7,500 grant?

Yes, provided the model is MCS-listed and fitted by an MCS-certified installer. The standard Boiler Upgrade Scheme grant is £7,500 for air source heat pumps in England and Wales. The £9,000 rate applies only to homes currently heated by oil or LPG that have no mains gas connection, on applications between 21 July 2026 and 31 March 2027.